1. Field of the Invention
The present invention relates to a document requesting and providing system formed by a document providing computer for providing a document managed therein to another computer connected with it via a network, and a document requesting computer for requesting a document managed by another computer connected with it via a network.
2. Description of the Background Art
A known document providing scheme for providing documents to unspecified many persons includes the WWW (World Wide Web), which is a document providing program for providing pre-stored documents in response to requests from other programs.
In general, a technique for linking a whole or a part of one document with another document is known for the purpose of attaching detailed explanation or related information with respect to that document or a phrase in that document. Documents which are linked together in this manner are collectively referred as a hypertext.
In the hypertext document, a user can selectively obtain detailed explanation or related information according to his need. In general, documents constituting the hypertext document are not necessarily limited to documents owned by the same owner, documents stored in the same computer, or documents stored in computers managed by the same organization.
As for the linking between documents, the following two cases are possible. The first case is a case of linking an own document A to another document B. To this end, it suffices to provide a document format having a function to specify the link from the own document A to the reference target document B, an identifier for uniquely specifying the reference target document, and a document subscription program having a function to retrieve the reference target document according to the document specifying the link. A known example for this type of document linking is realized by the HTML (HyperText Markup Language) as the document format, the URL (Uniform Resource Locator) as the identifier, and the Mosaic as the document browsing program.
The second case is a case of linking from another document B to an own document A. In a conventional document providing scheme such as the WWW, no function for attaching a link to the specified document A from another document B is provided, so that either one of the following schemes have to be adopted in order to realize this type of document linking.
(1) The document B should be stored in a state capable of being changed by anyone, and the owner of the document A should attach a link from the document B to the own document A by changing the document B. PA1 (2) A provider of the document B should be requested to change the document B, and in response the provider of the document B should attach a link from the document B to the document A.
However, these schemes (1) and (2) are associated with the following problems. Namely, the scheme (1) has a problem in that there is a possibility for the alteration of the provided document content by a third person. Moreover, the computer storing the document B has to be set open to unspecified many persons, so that there is also a problem regarding the security. On the other hand, the scheme (2) has a problem in that the provider of the document B has to carry out the operation to attach a link to another document each time a request is received, so that tedious operations have to be required to the provider of the document B.